# 1209. Remove All Adjacent Duplicates in String II

https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii

## Description

You are given a string `s` and an integer `k`, a `k` **duplicate removal** consists of choosing `k` adjacent and equal letters from `s` and removing them, causing the left and the right side of the deleted substring to concatenate together.

We repeatedly make `k` **duplicate removals** on `s` until we no longer can.

Return the final string after all such duplicate removals have been made. It is guaranteed that the answer is unique.

**Example 1:**

```
**Input:** s = "abcd", k = 2
**Output:** "abcd"
**Explanation:** There's nothing to delete.
```

**Example 2:**

```
**Input:** s = "deeedbbcccbdaa", k = 3
**Output:** "aa"
**Explanation:**First delete "eee" and "ccc", get "ddbbbdaa"
Then delete "bbb", get "dddaa"
Finally delete "ddd", get "aa"
```

**Example 3:**

```
**Input:** s = "pbbcggttciiippooaais", k = 2
**Output:** "ps"
```

**Constraints:**

* `1 <= s.length <= 105`
* `2 <= k <= 104`
* `s` only contains lower case English letters.

## ac

```java
```
